On Monday, minor flooding is forecast for the Comal and Guadalupe Rivers at New Braunfels and Cibolo Creek at Selma; Salado Creek is expected to flood to moderate levels at Loop 13. In Wimberly, the Blanco River could surge above flood level Monday afternoon but is expected to quickly return to normal thereafter.

On Monday night, minor flooding is expected of Leon Creek at Interstate 35 South, and the Medina River at U.S. 281 South, along with moderate flooding of the San Antonio River at Elmendorf.

Mild to moderate flooding is expected later in the week to the southeast; the San Antonio River and Cibolo Creek are both expected to flood near Falls City on Wednesday, according to the National Oceanic and Atmospheric Administration's Advanced Hydrologic Prediction Service.

6:50 p.m.: Several area roads are closed due to flooding as storms moved across San Antonio.

South Hausman Road is closed from Prue Road to Champion's Gate. Leslie Road is closed from Loop 1604 to Braun Road.

As of 6 p.m., photos on Twitter showed flooding had begun on Interstate 10 near Camp Bullis — the same stretch of road in which a driver was washed away and killed during flooding in late October 2015.

At 6:20 p.m., the National Weather Service tweeted that the main line of thunderstorms stretched from Pearsall to Kerville to Llano, largely avoiding San Antonio.

5:30 p.m.: The National Weather Service has extended a flash flood watch for most of South Central Texas until 10 a.m. Tuesday.

Areas south of San Antonio, including Pleasanton, Jourdanton and Poteet, were under an extended thunderstorm warning, which was expected to expire at 5:30 p.m.

The severe weather affected thousands of residents in San Antonio, as CPS Energy reported more than 12,822 customers were without electricity because of power outages across the Alamo City.

The company's power outage map showed 147 outages at 5:30 p.m.

Additionally, a traffic light at the Loop 1604 and Bandera Road was reported down, according to police chatter. Several other intersection traffic lights were reported down in North San Antonio.

4:30 p.m.: The National Weather Service issued a tornado warning for portions of Atascosa County, south of Bexar County.

The report noted a severe thunderstorm capable of producing a tornado was located near Charlotte and moving north at 5 mph. Hail was also observed with this storm.

Noon: While projected heavy storms have yet to hit the San Antonio area, The Austin American Statesman is reporting that more than 5 inches of rain has fallen in Bastrop County forcing the closure of Texas 21 near Paige, Texas.

San Antonio remains under a flash flood watch until 10 a.m. Tuesday.

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Heavy rain and flash flooding along with winds of up to 60 miles per hour could ruin Fiesta celebrations Sunday and Monday as local and state agencies are preparing to provide aid throughout the state.

Gov. Greg Abbott announced that the Texas State Operations Center will be elevated to Level 3 activation at 7 a.m. Sunday as heavy rain and potential flooding is forecast to impact parts of Texas.

"We urge all Texans to closely monitor developing weather as the state prepares for the possibility of heavy rainfall, tornadoes and flooding," Abbott said. "It is crucial that Texans stay clear of rising waters and heed warnings from state and local officials, who stand ready to assist and support communities impacted as this weather system passes through Texas."

The National Weather Service is expecting 1 to 3 inches of rain throughout South Central Texas, with an isolated 7 to 10 inches possible in areas east and northeast of Fredericksburg to Pearsall.

NWS meteorologist Cory Van Pelt said the heaviest rain is expected to fall Sunday and Monday with a flash flood warning scheduled to begin at 10 a.m. which continues through Tuesday.

"It looks like it will increase in intensity by the early afternoon, with more of the same for the evening," Van Pelt said. "It'll come down a little bit later on that night, but not shut off completely."

The service is also monitoring the slight chance for tornadoes and hail, which is not expected to be as damaging as what fell over the area Tuesday, if at all present.

Fiesta events scheduled when the brunt of the rain is expected Sunday include the Fiesta de los Reyes at Market Square, the Taste of New Orleans at the Sunken Garden Theater. Monday's rain is expected to impact the Texas Cavaliers River Parade on the San Antonio River Walk.

The last river parade canceled by rain was the 34th Annual Ford Holiday River Parade on Nov. 27, which was shut down as it began. A total 1.47 inches of rain was recorded that night, according to the NWS website.

Van Pelt said Monday looks to be just as wet continuing from the late morning and well into the evening. He said it's important to stay inside if possible and keep an eye on weather developments.

"It's good not to be out because you don't want people getting trapped by flooding and low water crossings," he said. "If you live near creeks and rivers make sure you have a way of getting warnings from more than one source."

The rain isn't expected to bring any temperature relief either, Van Pelt confirmed, noting its expected to be humid with high and low temperatures in the 70 degree range.

Rain chances are not expected to decrease until Wednesday and through the end of the week. Clouds are expected to linger with a 30 to 40 percent chance of rain until the weekend.